The present invention relates to a conveyor system and, more particularly, to a system that includes a workpiece carrier plate and a belt conveyor that transports the plate and workpiece.
Manufacturing facilities, particularly automobile assembly plants in Europe, have for some time used moving pallets or skillets to conveyor large parts such as vehicle bodies. The skillets are larger than the workpiece so as to permit a worker to ride the skillet along with the workpiece and to perform a production task as the skillet passes through a production area.
A representative prior art configuration of a plurality of skillets within a production area is shown in FIG. 1. The skillets 10, 12, and 14 are moved through the production area in a train such that adjacent skillets abut one another. The train is driven by friction drive assemblies which may include opposed drive mechanisms 18 and 20 located at the entrance to the production area. Each drive assembly has friction wheels that are positionable to engage the sides of the skillets and push the skillets forward in an end-to-end train through the production area. Retarding friction drives 24 maintain the abutting relationship of the skillets within the production area while acceleration drives 26 may be used to accelerate the skillets exiting the production area. Each skillet also includes wheels 28 that extend from the underside of its platform and ride on guide rails.
The skillet itself has robust construction that provides a sturdy platform for the workers, sufficient structural strength to accommodate the loadings, and a side surface depth that permits engagement by the friction drive wheels. To achieve the desired strength, skillets commonly include a robust steel frame and wood decking. While a robust design is generally necessary to accommodate the operational requirements of existing skillet systems, the strength comes at a cost, greater weight and expense. Moreover, the guide rails, friction drive assemblies, and other components of existing skillet systems are correspondingly robust, heavy, complex, and costly.
A further deficiency in the art with respect to friction driven skillet systems relates to maintaining the skillets in end-to-end abutting relationship throughout the production area. Specifically, despite the use of retarding drives, non-uniform movement of skillets within the train can create gaps between adjacent skillets. These gaps interrupt the continuity of the worker platform. The depth of existing skillets and the necessity for installation pits can create undesirably large elevation drops in the gaps.